Penton Mint 400 starting

[Stuttgartautoman]

Any tips for kickstarting a Mint 400 that does not have a compression release? I'm aware of kicking it through and getting the piston just past TDC. It's just so difficult to kick over sharply. Chicago Jerry has done his combustion chamber mod to the head already. Thank you for any tips.

[KJDonovan]

Stu,

I previously had a 400 that was a bear to start, and I ended up running a piece of 1/8" overflow tube from one of the 38MM Bing overflow ports up under the tank and tied it off on the handlebars.  Just before starting, I would lightly blow into the tube which would push fuel and vapors into the cylinder, and it generally fired on 1st kick.  Don't know what you're running for a carb, but if it's a Bing, it's worth a try.

Thanks,

Kevin

[Stuttgartautoman]

I'm running the stock 38mm Bing. My issue seems to be I can't kick it hard enough, or quick enough due to the compression. With the tickler it seems to be getting plenty of fuel to start. It will compression start in 4th or 5th gear on a hill but the lower gears just lock up the rear wheel.

[KJDonovan]

Stu,

If it has so much compression you can't kick it through, you may want to increase the deck height (distance between the top of the compression ring and the top of the cylinder) by installing a thicker base gasket or gaskets.  I believe that the manual calls for .040" (1MM) deck height, you probably want to see what yours is set at.  Increasing deck height will reduce compression which should make it easier to kick over.

Thanks,

Kevin

[Stuttgartautoman]

Kevin, my deck height is set to stock specs as well as the ignition timing. I spoke to Chicago Jerry about putting a thicker base gasket under the cylinder to reduce compression but he discouraged this as it alters port timing.
Thank you

[Daniel P. McEntee]

Kevin, my deck height is set to stock specs as well as the ignition timing. I spoke to Chicago Jerry about putting a thicker base gasket under the cylinder to reduce compression but he discouraged this as it alters port timing.
Thank you

    If this is a fresh rebuild, it just needs some time on the engine. if you know some one that has the "leg" you need to get it to fire, invite him or her to go riding, get it started, and try to get at least an hour of easy does it riding on it. id you can find a long gravel road where you can get it into 3rd and 4th gear to get the RPMS to run consistently, that would be the best thing for it. Let it cool till cold in between runs and repeat until you get at least an hour on it, and I think you will see an improvement. Some paper shims under the head gasket may be enough to take the edge of it for this also and not alter the port timing, and can easily be removed later.
    Type at you later,
   Dan McEntee

[Stuttgartautoman]

Dan,
Thank you, good advice. It is a fresh rebuild although believe it or not the bike only has 239 original miles on it and last ran in 1975. The piston and bore both looked perfect so it just has new rings. The upper ring had developed some rust pits and was stuck in the groove but the piston measured out fine. I have had it running but never by kickstarting. I compression started it down a hill but only ran it for like 45 seconds total so far. It's a bear to kick over for sure especially with the left side kick lever, which for me means I have to stand next to the bike to kick with my right leg. I'll keep you all posted.

[Doug Knight]

I have a 250 that I could not start. This was a complete rebuild with a Motoplat that was tested and remagnitized twice. Still wouldn't start. Just pop once in a while. Hip replacements while nice, do have their limits. Purchased and mounted a PowerDynamo(Vape) complete ignition. Started on second or third kick. I have their ignitions on all my Pentons now.

Adding .020 to the base sightly changes the deck height. You are changing port timing of both (intake and exhaust) at the same time. Just not enough to notice unless you are riding at a very high level. Then that would mean you could start the monster in the first place. I have about .015 added on the 250 and seems fine.

On another note I have one hip replacement and getting the other done in a few weeks. So I'm done. Will be posting all my Pentons come spring, I'm in Montana and locked in winter here.

I regret never riding or racing a Mint, as I raced a 100, 125, 175, and the 250 back in the 70's.

[Stuttgartautoman]

Doug, thanks for the info. I have a good friend in Portland looking for a Penton to use in AHRMA events. Please let me know what models you have and when you will be selling them and I'll forward information to him. Sorry about your hips. Hope you got a lot of fun riding in.
Sincerely, Mike Jordan Prineville, Oregon

[Rdway60]

Can you add a compression release?

[Stuttgartautoman]

As a last resort I can but the bike is 100% original so was trying to avoid that. Figured if I couldn't start it easily to ride it that was most of the fun. 😎 It's a non primary kickstart also so has to be in neutral to kick over so definitely don't want to stall it.

[Doug Knight]

Showroom original or race original. Back in the day we changed a lot of the features to make the bikes work for us. The term "Ready to race" while a modern term, did no apply then. With a little prep I could make water crossings completely submerging the engine on a hugh breather. Remember Pentons did not come with spark arresters. And a lot of exhausts were cut. Even Penton (High-Point) sold accessories. If you are racing, don't get caught up on original. That's for keeping in your living room on show. I have one bike that did come from someone's living room.

[Stuttgartautoman]

This Mint 400 is extremely original but not showroom or museum condition. 239 original miles still had the original Metzeler tires and tubes on it. Last ran in 1975 until I resurrected it a few months ago. Has some vintage patina of course, my goal was to preserve it in as original condition as possible. Having said that, I will ride it and race it and ultimately do whatever is necessary to make it kick start reliably. Maybe even do leg presses at the gym. 😳

[slvrbrdfxr]

Mike,
As far as starting your bike, there are a lot of good suggestions so far in regards to the verifying the deck height and possible ignition issues. If you're running a Motoplat, the stator and coil need to have VERY good ground paths in order to get a good hot spark from these ignitions. Make sure the grounding points at the frame to engine, stator plate to engine and coil to frame are shiny clean bare metal and then apply some dielectric grease to these areas at assembly. Also, as someone already mentioned the magnets in the Motoplat flywheel could be weak and it may possibly need to be remagnetized(if you can find someone with the proper equipment to do it). You might also try running separate a 12gauge ground wire from the stator mount plate up to the coil bracket to ensure a good ground path between all the components. As far as kicking the bike over, my leg strength isn't what it used to be years ago. These days when I'm going to cold start my Mint 400, I stand on a milk crate on the left side of the bike(kicking with right leg) which gives me much more leverage to give the kickstart lever a good crisp stroke. Seems to help me out a lot and then once the bike is warm it usually fires off pretty easy without use of the milk crate. If your buddy is in the market for a bike, I still have a Mint 400 and 75 Jackpiner listed for sale on page 2 of the site's Wanted/For Sale section. I'm away from home right now but will see if I have a few spoke nipples once I get back in a week or so. Keep us updated on your progress.
Dave McCullough

[Stuttgartautoman]

Thanks Dave for the info. I have checked all the grounds and the bike does have strong spark. I use the same method for kicking using a crate on the left side of the bike. Your two bikes look very nice. My friend is looking for a 125 6 Day or 175 Jackpiner, but I think he thought your bikes looked too nice to ride.